Introduction to AR-15 Ammunition and Magazines

Introduction to AR-15 Ammunition and Magazines

Posted by STNGR USA on Oct 11th 2022

We've talked about the AR-15. Let's talk about the bullets it shoots.

Intro to AR-15 Ammo and Magazines

Hello and welcome to the STNGR Workshop. My name is Rick Barrett and I'm your host for these series of videos where we talk about everything in the gun community, from gun accessories to gun maintenance. We are continuing our series on the AR-15. Now in today's video, we are going to be talking about the bullets it shoots as well as the magazines that hold them. As with previous videos, this is not gonna get into the nitty-gritty of every single detail. This is to give you an overall starting point when getting into the AR-15 platform.

I'm gonna start this video talking about the components in a bullet cartridge, but after that, I'm going to refer to it as ammunition. Now, bullet cartridge is the professional term for it. But in gun stores and in common language it will be referred to as ammunition or ammo. That out of the way, let's talk about the bullet cartridge of the AR-15.

AR-15 Bullet Cartridge / Ammo

So what is a bullet cartridge or ammo? A bullet cartridge is four interlocked components that make up a single round of ammunition.

These are: the casing, the primer, the propellant, and the projectile.

  • The casing holds the gun powder, the primer, and the projectile together. People will call it the brass.
  • The next part is the primer which is sealed at the base of this cartridge and creates the spark that ignites the propellant.
  • Once that propellant is ignited, it explodes in a controlled way and pushes the projectile forward.
  • Finally, the projectile (sometimes referred simply as the bullet), is the part of the cartridge that flies through the air towards your target.

As stated before, now that we know what a bullet cartridge is, for the sake of common language, I'm gonna be referring to it as ammo throughout the rest of this video.

Anatomy of a Cartridge. Image from Range365.

Full Metal Jacket vs Hollow Point Ammunition

The next thing you're gonna wanna know when selecting ammunition for your AR-15 is there's two general types: full metal jacket and hollow point.

The first type of ammo is called full metal jacket or FMJ. All you need to know when you start out is these rounds are optimal for practice and not for home defense and not for hunting.

The second type of ammo is called hollow point, but it can also be referred to in several other ways such as jacketed hollow point or soft points. Now, these are great choices for your home defense purposes. This bullet is designed to inflict increased damage when it strikes a target and this is achieved through greater expansion once the target is impacted.

That is your big difference between the two types of bullets. FMJ bullets do not expand that much, whereas your hollow point bullets expand after impact.


Full Metal Jacket (FMJ) vs Hollow Point (HP) Ammunition. Image from

Top 3 Most Common AR-15 Rounds

Because the AR-15 has been in military service since the Vietnam War, there are a lot of different types of calibers, different powers, and variations of the bullet and the platform. We could spend an entire hour talking about the different types and not really scratch the surface.

So for the sake of time, we're gonna talk about the top three most common AR-15 rounds. We're gonna go from third most common or useful AR-15 rounds to the most popular (and I think you guys will have an idea what the most popular one is).

6.5 mm Grendel

But to get there we should go through two other kinds of useful or common AR-15 rounds that people use, the first being the 6.5 mm Grendel. Now the 6.5 Grendel is used for big game such as deer, antelope, and all but gargantuan black bears.

Federal American Eagle Varmint and Predator Ammunition 6.5 Grendel 90 Grain Hollow Point. Image from Midway USA.

.300 AAC Blackout

After the 6.5 Grendel the second most common or useful AR-15 round is the 300 Blackout AAC. Now the 300 Blackout AAC functions perfectly with the standard AR-15 bolts, magazines, and everything else. All you need is a new barrel.

Now the biggest advantage the 300 Blackout has is that when it is paired with a quality suppressor the cartridge can be very quiet indeed, which makes it very popular for hunters.

Sig Sauer Elite Performance Match Grade Ammunition 300 AAC Blackout 125 Grain Open Tip Match. Image from Midway USA.

5.56 NATO / .223 Remington

Now it's not a surprise that the 5.56 NATO / .223 Remington round comes in as the most common or useful AR-15 ammo, simply because this ammo has been around since the invention of the AR-15 rifle. As a result of being around for over half a century, the 5.56 NATO / .223 Remington round have become far more capable than their original design could have ever hoped. No matter what you're trying to do, whether it's self-defense, hunting, or sport shooting, the 5.56 NATO / .223 Remington round is the most common, or some people would say, capable round that the AR-15 has to offer.

.223 Remington Ammunition (L) and 5.56 NATO Ammunition (R). Image from

When You Can Use 5.56 NATO vs .223 Remington

Now one quick point, even though they are linked together (and it's gonna get a little confusing at this point) you cannot interchange the rounds. Now just stay with me for a second.

You can shoot a .223 Remington round out of a 5.56 barrel. So if your AR-15 is chambered in 5.56, you can shoot both 5.56 and .223 out of that barrel.

However, if you have a .223 Remington rifle (which is not as common as it used to be, but they still exist), you cannot, cannot shoot a 5.56 NATO round out of it. It's gonna be a bad day for you if you do.

So, yes to a .233 in a 5.56 barrel. No to a 5.56 in a .223 barrel.

AR-15 Magazines

Now that we've discussed bullet cartridges or ammo, let's talk about where they're stored, which is the AR-15 magazines. Now it is important to know that there is no such thing as an AR-15 clip. A lot of people will use the terms interchangeably but that's not correct. A clip is designed for a different type of rifle. The only system that works in an AR-15 platform are magazines.

What To Look For in an AR-15 Magazine

So when you're looking at AR-15 magazines, there's really two things you want to look at: durability and performance.

When it comes to durability, you have to understand that the magazines of your AR-15 are going to take a lot of punishment. Whether they're at training courses, whether you are out hunting, or maybe you're just having fun at the range, you're gonna wanna pick higher quality AR-15 magazines that aren't gonna break on you.

The second thing you want to look at when it comes to AR-15 magazines is performance. Now, despite the fact that they all look the same, there is a difference in quality and that quality is going to give you better performance when it comes to using your AR-15 because the last thing you want is the object that feeds the ammo into your gun to not work in less than ideal circumstances.

When we talk about the performance, we talked about performing in less than ideal circumstances, that's gonna come down to build material and quality. So durability and performance are going to be linked together in the type of magazine that you choose.

Choosing an AR-15 Magazine

The gold standard for a AR-15 magazines is the Magpul PMAG. Whether it comes to durability performance and value, the Magpul PMAG has carved itself out as the standard bearer for the AR-15 magazines. Some are more expensive, some are less expensive, but when it comes down to it, most people will tell you that the Magpul PMAG is the best one out there.

Now, this doesn't mean you can't try other magazines, just understand that if you go for a cheaper magazine it may run fine, but the first time it drops to the ground it may break. So you've wasted your money there. And when it comes to more expensive magazines, the build quality may be a tiny bit better, but if it runs flawlessly like a Magpul or some of the other mid-tier brands, then you're really wasting your money on the name and nothing more.

Magpul PMAG® 30 AR/M4 GEN M3® Window. Image from Magpul.

Final Thoughts

And that's it for this video. We've discussed what a bullet cartridge is, different types of AR-15 ammo, and the magazines that are used to hold them.

My name is Rick Barrett coming to you from the STNGR Workshop. I hope you enjoyed this video and I'll talk to you soon.